Treatment of humeral condylar fractures and humeral intracondylar fissures in cats with patellar fracture and dental anomaly syndrome

A 3D Printed Anatomically Pre-Contoured Plate for the Treatment of Y-T Humeral Condylar Fractures: A Feline Cadaveric Study

(1) Background: Anatomically pre-contoured plates usually require only minimal or even no intraoperative contouring. For complex cases, such plates also assist the surgeon as an anatomical template during fracture reduction. In this study, we present our experience of using a 3D printing technology for the treatment of bicondylar humeral fractures in feline cadavers. (2) Methods: Surgeries were performed on 15 pairs of front limbs amputated at the scapula. The limbs were obtained from 15 adult cats without obvious pathology of the skeleton. After flexion of the elbow and subperiosteal elevation of the anconeus muscle, the humeral Y-T fractures were created using a bone chisel and mallet. A custom-made anatomically pre-contoured interlocking plate was used to reduce and stabilise the medial aspect of the humeral condyle to the humeral diaphysis. After reduction of the humeral condyle, a positional locking screw was then inserted from the medial to the lateral side and a straight 2.4/2.7 interlocking bone plate was used to stabilise the lateral part of the condyle to the humeral diaphysis. (3) Results: The length of the humerus ranged from 98.2 to 107.0 mm and did not differ significantly between the left and right bone. The diameter of the isthmus of the humeral condyle ranged from 5.2 to 5.5 mm and did not differ significantly between the left and right bone. In all 30 limbs, bicondylar fracture was accompanied by epicondylar comminution. In 7/30 limbs (4 left, 3 right) the fracture of the humeral shaft was also present. In the left limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 11/15 cases, moderate (1-2 mm) in 2/15 cases and large (>2 mm) in 2/15 cases in which the condylar screw was incorrectly inserted. In the right limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 14/15 cases and moderate (1-2 mm) in 1 case. (4) Conclusions: 3D printing and the technology of metal powder sintering offers a wide range of possibilities for the development of new surgical implants. The anatomically pre-contoured bone plate appears to be a valuable tool in the reduction and stabilisation of Y-T humeral fractures in adult domestic cats weighing 3.0 to 4.5 kg.

Defining the safe corridor for transcondylar screw placement in the feline humeral condyle

OBJECTIVES

The aim of this study was to develop guidelines for the optimal location of drill entry and exit points for insertion of a transcondylar screw across the feline humeral condyle.

METHODS

Multiplanar reconstruction of feline elbow CT scans performed between 2016 and 2021 at one referral institution were reviewed. The optimum medial and lateral epicondylar entry and exit points for transcondylar screw placement were determined. These values were normalised to the humeral condylar diameter (HCD) for each elbow to determine the transcondylar screw placement guidelines. These guidelines were applied to each elbow and tolerance angles were determined in the transverse and frontal plane CT images to determine the safe corridor for screw placement.

RESULTS

Twenty elbows from 12 cats were evaluated in this study. The guidelines for transcondylar screw placement were as follows: the medial entry/exit point was 0.38 × HCD cranial and 0.16 × HCD distal to the medial epicondyle, and the lateral entry/exit point was 0.3 × HCD cranial and 0.16 × HCD distal to the lateral epicondyle. Tolerance angles were statistically significantly (P <0.05) larger in both frontal (34.5% larger) and transverse (21.1% larger) planes when drilled from a lateral to medial direction compared with drilling from a medial to lateral direction.

CONCLUSIONS AND RELEVANCE

The guidelines determined from this study may aid clinicians in the placement of humeral transcondylar screws in cats. Where possible, drilling from a lateral to medial direction is recommended owing to the higher tolerance angles reducing the likelihood of articular surface damage. Further studies are warranted to determine whether these guidelines are clinically useful and result in the safe insertion of a transcondylar screw in the clinical setting.

Analysis of feline humeral fracture morphology and a comparison of fracture repair stabilisation methods: 101 cases (2009-2020)

OBJECTIVES

The aims of this study were to describe the type, presentation and prognostic factors of feline humeral fractures over a 10-year period and to compare three stabilisation systems for feline humeral diaphyseal fractures.

METHODS

In total, 101 cats with humeral fractures presenting to seven UK referral centres between 2009 and 2020 were reviewed. Data collected included signalment, weight at the time of surgery, fracture aetiology, preoperative presentation, fixation method, surgical details, perioperative management and follow-up examinations. Of these cases, 57 cats with humeral diaphyseal fractures stabilised using three different fixation methods were compared, with outcome parameters including the time to radiographic healing, time to function and complication rate.

RESULTS

The majority of the fractures were diaphyseal (71%), with only 10% condylar. Of the known causes of fracture, road traffic accidents (RTAs) were the most common. Neutered males were over-represented in having a fracture caused by an RTA (P = 0.001) and diaphyseal fractures were significantly more likely to result from an RTA (P = 0.01). Body weight had a positive correlation (r = 0.398) with time to radiographic healing and time to acceptable function (r = 0.315), and was significant (P = 0.014 and P = 0.037, respectively). Of the 57 humeral diaphyseal fractures; 16 (28%) were stabilised using a plate-rod construct, 31 (54%) using external skeletal fixation and 10 (18%) using bone plating and screws only. Open diaphyseal fractures were associated with more minor complications (P = 0.048). There was a significant difference between fixation groups in terms of overall complication rate between groups (P = 0.012). There was no significant difference between fixation groups in time to radiographic union (P = 0.145) or time to acceptable function (P = 0.306).

CONCLUSIONS AND RELEVANCE

All three fixation systems were successful in healing a wide variety of humeral diaphyseal fractures. There was a significantly higher overall complication rate with external skeletal fixators compared with bone plating; however, the clinical impact of these is likely low.

Chronic paronychia in cats with patellar fracture and dental anomaly syndrome

CASE SERIES SUMMARY

The aim of this case series was to describe the clinical features and treatment of paronychia in cats diagnosed with patellar fracture and dental anomaly syndrome (PADS). Clinical records, photographs, microbiology, cytology and histopathology reports were collected, and follow-up was obtained. Five cats with paronychia were included. All five cats had multiple digits of multiple limbs affected and eventually underwent amputation of the third phalanx of one or multiple digits. A total of 36 digits were affected, 17% (n = 6/36) resolved with medical management and 83% (n = 30/36) were eventually treated successfully by amputation. The cats had treatment with numerous courses of antibiotics (range 7-20; mean 11 courses) over periods of time ranging from 10 to 67 months (mean 32 months).

RELEVANCE AND NOVEL INFORMATION

Chronic paronychia may be an additional clinical feature of PADS and the probable mechanism involves poor integrity of osteopetrotic bone, loss of normal nailbed anatomy and secondary osteomyelitis of the distal phalanx. Medical management with antibiotics, anti-inflammatory therapy and steroid treatment may improve the clinical signs in the short term; however, in severe instances, amputation of the third phalanx of the affected digit seems to be necessary to resolve repeated recurrences and discomfort. Additional information on the long-term outcome is required. In any cat with atraumatic patellar fractures and/or retained deciduous teeth, paronychia may require surgical management if medical management is unsuccessful.

Patellar fractures in cats: Repair techniques and treatment decision-making

PRACTICAL RELEVANCE

While feline patellar fractures are not commonly encountered in practice, they tend to be found more often in younger cats; no breed or sex predispositions are recognised. If there is no evidence of a traumatic aetiology, the cat may be suspected of having patellar fracture and dental anomaly syndrome (PADS). Patellar fractures are easy to diagnose on lateral radiographs and there are several different fracture types. The type of fracture, the age of the cat at fracture occurrence and whether there is suspicion of a pathological aetiology are all relevant when considering treatment technique.

CLINICAL CHALLENGES

While some cats with patellar fractures will do well with conservative management, surgical treatment is often indicated and decision-making can be challenging.

EVIDENCE BASE

Information and recommendations provided in this review are based on the literature and the author's own clinical experience. There are several publications on PADS, but there is limited evidence as to what the underlying cause of this condition is, and the best method for managing patellar fractures is still an area where more research is needed.

AIM

This review aims to gather the papers, case series and case reports published over the past few decades in order to discuss how best to manage different types of patellar fractures.